JPH0337677A - Electrostatic charge image developing toner - Google Patents

Abstract

PURPOSE:To prevent staining of a toner carrier and to enhance storage stability by adding a positively chargeable fine silica powder to the outsides of a fine colored particles comprising the metal compound of an imidazole derivative, a dye or pigment and a binder resin as a charge controller. CONSTITUTION:The metal compound of the imidazole derivative is good in heat stability and does not degenerate at all from room temperature up to 250 deg.C. When this metal compound is incorporated in the toner, it is good in dispersibility in the binder resin, and an electrostatic charge quantity of the toner is high enough as compared with the case of using the imidazole alone, and the toner particles are uniformly charged among each particle, thus permitting the toner carrier to be prevented from staining, and storage stability to be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a toner for visualizing electrostatic latent images in image forming methods such as electrophotography and electrostatic recording.

[Prior Art] Conventionally, as an electrophotographic method, U.S. Patent No. 2,297°69
1, Special Publication No. 42-23910, and Special Publication No. 4
Various methods are described in Japanese Patent No. 3-24748 and the like.

The developing methods applied to these electrophotographic methods include:
Broadly speaking, there are dry development methods and wet development methods. The former method is further divided into methods using a two-component developer and methods using a one-component developer.

As toners applied to these dry developing methods, fine powders in which dyes and pigments are dispersed in natural or synthetic resins have conventionally been used. For example, particles obtained by dispersing a colorant in a binder resin such as polystyrene and pulverizing the particles to about 1 to 30 μm are used as toner. As the magnetic toner, one containing magnetic particles such as magnetite is used. Further, in the case of a system using a two-component developer, the toner is usually mixed with carrier particles such as glass beads and iron powder.

Either toner must have a positive or negative charge depending on the polarity of the electrostatic latent image being developed.

In order to make the toner retain an electric charge, it is possible to use the triboelectricity of the resin that is a component of the toner, but since the toner's chargeability is small in this method, the image obtained by development is likely to fog and become unclear. Become something. Therefore, in order to impart the desired tribo-1F electric property to the toner,
Dyes, pigments, and even charge control agents that impart chargeability are added.

Charge control agents known in the technical field today include nigrosine dyes, azine dyes, triphenylmethane dyes and pigments, quaternary ammonium salts, or quaternary ammonium salts with side chains as positive triboelectric chargers. Polymers that have the following properties are known.

[Problems to be Solved by the Invention] However, since some of these charge control agents tend to contaminate the snow or carrier, the amount of triboelectric charge of toners using them decreases as the number of copies increases. , causing a decrease in image density. Further, some charge control agents have an insufficient amount of triboelectric charge and are easily affected by temperature and humidity, which causes environmental fluctuations in image density. In addition, some charge control agents have poor dispersibility in resins, so
Toner using this type of toner has an uneven amount of triboelectrification between particles and is prone to fogging. Furthermore, some charge control agents have poor storage stability, and their triboelectric charging ability decreases during long-term storage. Additionally, some charge control agents are colored and cannot be used in color toners.

At present, there is a strong demand for the development of a charge control agent that satisfies all of these requirements.

[Means and effects for solving the problem] As a result of intensive studies to solve the above-mentioned problems, the inventors have added positively charged silica to a colored fine powder using a metal compound of an imidazole derivative as a charge control agent. It has been found that a toner to which fine powder is externally added has sufficient positive chargeability, is less likely to contaminate toner carriers such as carriers, and has good storage stability and is less likely to fog.

The imidazole derivative metal compound of the present invention has good thermal stability and does not deteriorate within the range from room temperature to 250°C. Furthermore, when the metal compound of the present invention is contained in the toner, the dispersibility in the binder resin is good, the toner charge amount is higher and sufficient than when the imidazole compound is used alone, and the toner particles The amount of charge between them is uniform.

Furthermore, color toners made with colorless or virtually colorless Ikudazole metal compounds have good dispersibility, so they do not impair the color of the image, and can be used with transparent sheets instead of copy paper. also has good translucency.

Furthermore, since the carrier is less likely to be contaminated, image density decreases due to carrier contamination in durability tests tend to be less than with conventional charge control agents.

Furthermore, it was found that this contamination could be almost eliminated by externally adding positively charged silica fine powder.

Further, by externally adding positively chargeable silica fine powder, roughness of the image is improved, and a high-density image can be obtained from the initial stage. However, when positively chargeable silica fine powder is not externally added, the image density rises poorly and blurring occurs, making it difficult to put it to practical use. Based on these findings, the inventors discovered that positively charged silica fine powder is indispensable and completed the present invention.

The imidazole forming the metal compound of the imidazole derivative of the present invention includes all imidazoles, but considering the high charge imparting ability, the following formula [I]-a,
b, the imidazole compound and anion shown in the formula [rB-a, b are preferred.

Considering ease of production, substituents R4 to R6 in the formula preferably have 24 or less carbon atoms, and more preferably have 6 or less carbon atoms.

[I] -a [1] -b[11]
-a [II b) Metals in the metal compound of imidazole derivatives include aluminum, chromium, manganese, iron, cobalt, nickel, copper, zinc, tin, lead, titanium, etc. Considering the high amount, zinc, titanium, nickel, iron, copper, chromium, and cobalt are preferable.
Zinc is more preferable in consideration of ease of production and color.

Further, the metal compound of the imidazole derivative of the present invention has a higher charge imparting ability than the imidazole derivative. The mechanism that provides this high charge-imparting ability is unknown, but it is thought to be due to the formation of a metal complex or metal salt via the nitrogen on imidazole.

Further, the metal compound of the imidazole derivative in the present invention has a counter ion as necessary. Counter anions in this case include inorganic anions and organic anions.

Inorganic anions include halogen ions such as F- and CI-, OH-, SO4''-, BF4-, DFsCl
<-,5iFa-also [Mo70z4]'-, [H2W
+204□] 10-[PMOL2040]3-, [
Examples include heteropolyacid ions such as PW120413-.

As organic ions, CI ""' sulfonic acid ion of C24, carboxylic acid ion of C1 to G24, C1 to G
24 sulfuric acid monoalkyl ester anions, tetraphenyl boron ions, and the like.

The imidazole metal compound of the present invention is synthesized by adding an imidazole compound, an imidazole alkali metal salt, or an imidazole alkaline earth metal salt to a metal salt solution, and if necessary, adding a reagent for exchanging counterions, and then purifying the compound. By doing so, the target compound is obtained.

If the number of moles of metal per gram of the product obtained is L, the number of moles of M5 imidazole compound is L, then the ratio M/L is 0.
．． A value of 0.05 or more and 2 or less indicates good positive chargeability, and a value of 0.16 or more and 0.6 or less is preferable in consideration of the thermal stability of the complex and the durability stability in a copy durability test when used as a toner.

Specific examples of the imidazole compound or imidazole anion forming the metal compound of the present invention are shown below.

shi2115 shii13 The metal compound of the present invention combines these imidazole species with 1 f
m or two or more types may be contained.

In the present invention, methods for incorporating the metal compound of the imidazole derivative into the toner include a method of adding it inside the toner and a method of adding it externally. The amount of these compounds used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner manufacturing method, including the dispersion method, and is not uniquely limited. However, it is preferably used in an amount of 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the binder resin. When adding externally, 0.0 parts by weight per 100 parts by weight of resin.
It is preferably 1 to 10 parts by weight, and it is particularly preferable to mechanochemically fix it to the surface of the toner particles. Further, the imidazole derivative metal compound of the present invention can also be used in combination with a conventionally known charge control agent.

In addition, as the silica fine powder forming a component of the developer in the present invention, silica fine powder manufactured by a dry method or a wet method can be used.

The dry method mentioned here is a method for producing fine silica powder produced by vapor phase oxidation of a silicon halide compound. For example, this method utilizes a thermal decomposition oxidation reaction of silicon tetrachloride gas in oxygen and hydrogen, and the basic reaction formula is as follows.

5iCf4+ 2 It2+ 02→510□+41(
Cj Also, in this manufacturing process, for example, it is also possible to obtain a composite fine powder of silica and other metal oxides by using other metal halide compounds such as alkium chloride or titanium chloride together with a silicon halide compound, These are also included.

On the other hand, various conventionally known methods can be applied to produce the silica fine powder used in the present invention by a wet method.

For example, the decomposition of sodium silicate with an acid can be expressed by a general reaction formula (the reaction formula is omitted below): Naz(lXsi02+1(Cj!+H20-5i0
2・ntl, O+NaC11 Other methods include decomposition of sodium silicate with ammonia salts or alkali salts, a method of generating alkaline earth metal silicate from sodium silicate and then decomposing it with acid to produce silicic acid, sodium silicate solution There are methods such as converting it into silicic acid using an ion exchange resin, and using natural silicic acid or silicate.

The silica fine powder referred to herein can be any of anhydrous silicon dioxide (silica) and other silicates such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, and zinc silicate.

Among the above silica fine powders, the specific surface area due to nitrogen adsorption measured by the BET method is 301112/g or more (especially 50~
4 oom'/g) is preferable as the matrix silica.

As a method for obtaining positively chargeable silica fine powder, the above-mentioned untreated fine silica powder is treated with a silicone compound such as silicone oil, silicone varnish, or silicone resin having an organo group having at least one nitrogen atom in the side chain. There is a method of treating with a nitrogen-containing silane coupling agent, a method of treating with a nitrogen-containing silane coupling agent, or a method of treating with a combination of these.

In the present invention, positively charged silica refers to silica that has a positive triboelectric charge relative to the iron powder carrier when measured by a blow-off method.

As the silicone oil having a nitrogen atom in the side chain used in the treatment of silica fine powder, a silicone oil having at least a partial structure represented by the following formula can be used.

(In the formula, R1 represents hydrogen, an alkyl group, an aryl group, or a G-alkoxy group, R2 represents an alkylene group or a phenylene group, R3 and R4 represent hydrogen, an alkyl group, and R represents an aryl group. The above alkyl groups, aryl groups, alkylene groups, and phenylene groups (including nitrogen heterocyclic groups) may have a nitrogen atom-containing organoleptic group, or may be substituted with halogen, etc., within a range that does not impair chargeability. It is okay even if it has a group.

Further, the nitrogen-containing silane coupling agent used in the present invention generally has a structure represented by the following formula.

R,,5iYn (R represents an alkoxy group or a halogen, Y (represents a 4-amino group or an organo group having at least one nitrogen atom, m and n are integers of 1 to 3, and m+n=4
It is. ) Examples of the organo group having at least one nitrogen atom include a main group having an organic group as a substituent, a nitrogen-containing heterocyclic group, or a group having a nitrogen-containing heterocyclic group. Examples of the nitrogen-containing heterocyclic group include an unsaturated hetero 1lJ1 group and a saturated heterocyclic group, and each of the known ones can be applied. Examples of the unsaturated heterocyclic group include the following.

Examples of the saturated heterocyclic group include the following.

The heterocyclic group used in the present invention is preferably a five-membered ring or a six-membered ring in consideration of stability.

Examples of such treatment agents include ayonobrobyltrimethoxysilane, aminopropyltriethoxysilane, dimethylacnobrobyltrimethoxysilane, diethylaminopropyltrimethoxysilane, dipropylaminopropyltrimethoxysilane, and dibutylaminopropyltrimethoxysilane. Propyltrimethoxysilane, monobutylaminopropyltrimethoxysilane, dioctylaminopropyltrimethoxysilane, dibutylaminopropyldimethoxysilane.

Dibutylaminopropylmonomethoxysilane, dimethylaminophenyltriethoxysilane, trimethoxysilyl-γ-propylphenylamine.

There are trimethoxysilyl-γ-propylbenzylamine, etc. Furthermore, as the nitrogen-containing heterocycle, those having the above-mentioned structure can be used. Examples of such compounds include trimethoxysilyl-γ-propylpiperidine, trimethoxysilyl -γ-propylmorpholine, trimethoxysilyl-γ
- Propylimidazole, etc.

The applied amount of these treated silica fine powders exhibits an effect when the amount is 0.01 to 20% based on the weight of the developer, and particularly preferably when it is added in an amount of 0.03 to 5%, excellent stability is achieved. It exhibits positive chargeability. A preferred form of addition is that 0.01 to 3% by weight of treated silica fine powder based on the weight of the developer is attached to the surface of the toner particles.

Furthermore, the silica fine powder used in the present invention may be treated with a silane coupling agent or a treatment agent such as an organosilicon compound for the purpose of hydrophobization, if necessary, and a known method may be used. , treated with the above-mentioned treatment agent that reacts with or physically adsorbs the silicate fine powder. Examples of such treatment agents include hexamethyldisilazane, trimethylsilane,
trimethylchlorosilane, trimethylethoxysilane,
Dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, allyl phenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane Silane, triorganosilylmercaptan, trimethylsilylmercaptan, triorganosilylacrylate, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane, diphenyljethoxysilane, hexamethyldisiloxane, 1.3-divinyltetramethyldisiloxane, 1. 3
-diphenyltetramethyldisiloxane, and dimethylpolysiloxane having 2 to 12 siloxane units per molecule and containing one Si-bonded hydroxyl group in each unit located at the end. These are 1 f!
It can be used alone or in a mixture of two or more.

Finally, the degree of hydrophobicity of the treated silica fine powder was determined to be 30 as measured by methanol titration test.
When the developer is hydrophobized so as to exhibit a value in the range of 80 to 80, the amount of triboelectric charge of the developer containing such fine silica powder becomes sharp and uniformly positive, which is preferable. Here, in the methanol titration test, the degree of hydrophobization of the silica fine powder having a hydrophobized surface is confirmed.

The "methanol titration test" specified herein for evaluating the degree of hydrophobization of the treated silica fine powder is carried out as follows: 0.2 g of the sample silica fine powder is added to a volume of 2
50mj! Add to 50 ml of water in an Erlenmeyer flask.

Methanol is titrated from the burette until all of the silica is wetted. At this time, the solution in the flask is constantly stirred with a magnetic stirrer. The end point is observed when the entire amount of silica fine powder is suspended in the liquid,
The degree of hydrophobization is expressed as the percentage of methanol in the liquid mixture of methanol and water when the end point is reached.

Coloring agents used in the present invention include carbon black, lamp black, iron black, ultramarine blue, nigrosine dye, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine 6G, calco oil blue, chrome yellow, quinacridone, benzidine yellow, rose. Conventionally known dyes and pigments such as bengal, triarylmethane dyes, monoazo dyes, and disazo dyes and pigments may be used alone or in combination.

Examples of the resin used in the present invention include monopolymers of styrene and substituted products thereof such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene;
-Chlorstyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-methyl chloromethacrylate copolymer Polymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer , styrenic copolymers such as styrene-acrylonitrile-indene copolymers; polyvinyl chloride, phenolic resins, naturally modified phenolic resins, natural resin-modified maleic resins, acrylic resins, methacrylic resins, polyvinyl acetate, silicone resins, polyesters Resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumaron indene resin,
Petroleum-based resins can be used.

Further, crosslinked styrenic copolymers are also preferred binder resins.

Examples of comonomers for the styrene monomer in the styrenic copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, and methacrylate. Acid, monocarboxylic acid having a double bond such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylonitrile, etc. or substituted products thereof; e.g., maleic acid, maleic acid, etc. Dicarboxylic acids with double bonds and their substituted substances such as butyl acid, methyl maleate, dimethyl maleate, etc.; vinyl esters such as vinyl chloride, vinyl acetate, vinyl benzoate, etc.; e.g. ethylene, propylene, butylene Vinyl monomers such as ethylene olefins such as; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; Can be used alone or in combination.

As the crosslinking agent, compounds having two or more polymerizable double bonds are mainly used, such as aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; for example, ethylene glycol diacrylate,
Carboxylic acid esters having two double bonds such as ethylene glycol dimethacrylate and 1,3-butanediol dimethacrylate; divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide, and divinyl sulfone; and three or more vinyl Compounds having groups: can be used alone or as a mixture.

In addition, when using a pressure fixing method, it is possible to use a binder resin for pressure fixing toner, such as polyethylene,
Examples include polypropylene, polymethylene, polyurethane elastomer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ionomer resin, styrene-butadiene copolymer, styrene-isoprene copolymer, linear saturated polyester, and paraffin.

Furthermore, the toner of the present invention is used in combination with a carrier. As the carrier that can be used in the present invention, known carriers can be used, such as iron powder, ferrite powder, magnetic powder such as nickel powder, glass beads, etc., and carriers whose surfaces are treated with resin etc. Those who have done so will be listed. or,
Examples of the resin that coats the carrier surface include styrene-acrylic ester copolymer, styrene-methacrylic ester copolymer, acrylic ester copolymer, methacrylic ester copolymer, silicone resin, fluorine-containing resin, and polyamide resin. , ionomer resin, polyphenylene sulfide resin, or a mixture thereof can be used.

The toner of the present invention may contain additives as required. Examples of the additive include a lubricant such as zinc stearate, an abrasive such as cerium oxide or silicon carbide, or an abrasive such as aluminum oxide. Examples include fluidity imparting agents, anti-caking agents, and conductivity imparting agents such as carbon black and tin oxide.

Further, fine powder of a fluorine-containing polymer such as fine powder of polyvinylidene fluoride is also a preferable additive from the viewpoint of fluidity, polishability, charging stability, and the like.

In addition, in order to improve mold releasability during hot roll fixing, waxy substances such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, Sasol wax, paraffin wax, etc.
It is also one of the preferred embodiments of the present invention to add about 5% by weight to the toner.

In manufacturing the toner according to the present invention, the toner constituent materials as described above are sufficiently mixed using a ball mill or other mixer, then thoroughly kneaded using a heat kneader such as a hot roll kneader or an extruder, and then cooled and solidified. Preferably, the toner is obtained by , mechanical crushing, or classification; another method is to obtain the toner by dispersing the constituent materials in a binder resin solution and then spray drying; A polymerization toner production method in which a toner is obtained by mixing the desired monomer with a predetermined material to form an emulsified suspension and then polymerizing the resulting toner; Alternatively, in a so-called microcapsule toner consisting of a core material and a shell material, Methods such as a method of containing a predetermined material in the shell material, or both of these materials can be applied. Furthermore, the toner according to the present invention can be produced by sufficiently mixing desired additives with a mixer such as a Henschel mixer, if necessary.

The toner of the present invention can be used in all conventionally known methods for developing electrostatic charge images in electrophotography, electrostatic recording, electrostatic printing, and the like.

The imidazole metal compound of the present invention is colorless or light-colored and has good positive triboelectric charging properties. Further, by externally adding positively chargeable silica fine powder, it is possible to prevent the toner carrier from being contaminated by the imidazole metal compound, and it is also possible to improve the density uniformity of a solid image.

Therefore, the toner of the present invention is less likely to cause image quality deterioration due to continuous copying and can provide images with excellent density uniformity.

(Margins below) [Examples] The present invention will be specifically described below using Examples, but these are not intended to limit the present invention in any way. Note that all parts in the following formulations are parts by weight.

Further, the ratio between the number of moles M of the metal in 1 g of the metal compound and the number of moles of the imidazole compound is expressed as M/L.

After thoroughly mixing the above materials in a blender, they were kneaded in a 2@kneading extruder set at 150°C.

The obtained kneaded material was cooled and coarsely pulverized using a cutter mill, and then finely pulverized using a pulverizer using a jet stream.
The obtained finely pulverized powder was classified using a fixed wall type wind classifier.

Furthermore, the obtained classified powder was strictly classified and removed at the same time using a multi-division classifier (elbow jet classifier manufactured by 8 Iron Mining Co., Ltd.) that utilized the Coanda effect to achieve a volume average particle size of 11.8.
A fine powder of μm size was obtained.

0.4 part of positively charged hydrophobic dry silica (BET specific surface area: 130 m27 g) treated with silicone oil having an amino group was added to 100 parts of the obtained fine powder, and mixed in a Henschel mixer to obtain a positively charged toner.

Next, 5 parts of the obtained toner were mixed with 100 parts of a fluorine-acrylic coated ferrite carrier having an average particle size of 65 μI to prepare a developer.

This developer was applied to a commercially available color electrophotographic copying machine CLC-1 (
A copying test was carried out using a modified Canon machine in which the OPC photoreceptor drum was replaced with an amorphous silicon drum.

As a result, under the environmental conditions of 23°C and 60%, a bright blue image with a density of 1.35 was obtained from the initial stage, and 20,000
No deterioration was observed after copying.

Okinariyu Copper phthalocyanine pigment (C, I) in Example 1.

Pigment Blue 15) and 5 parts of quinacridone pigment (C
, 1, Pigment Red 122) A fine powder having a volume average particle diameter of 11.2 μm was obtained in the same manner as in Example 1 except that the amount was changed to 1 part, and silica was further mixed to obtain a positively charged toner.

Next, the same carrier as in Example 1 was mixed in the same ratio,
It was used as a developer.

This developer was subjected to a copying test in the same manner as in Example 1. As a result, a bright magenta image with a density of 1.33 was obtained from the initial stage under environmental conditions of 23° C. and 60%.

No deterioration in image quality was observed even after 20,000 copies were made.

Fruit 1041 Copper phthalocyanine pigment (C, I) in Example 1.

A fine powder with a volume average particle size of 11.6 μm was obtained in the same manner as in Example 1, except that 5 parts of Pigment Blue 15) was changed to 173.5 parts of C.1, Pigment Yellow, and silica was further mixed to form a positively charged toner. Obtained.

Next, the same carrier as in Example 1 was mixed in the same ratio,
It was used as a developer.

This developer was subjected to a copying test in the same manner as in Example 1. As a result, under environmental conditions of 23° C. and 60%, a bright yellow image with a density of 1.35 was obtained from the beginning. 2
No deterioration in image quality was observed even after 0,000 copies were made.

Example 4 Copper phthalocyanine pigment (C, I) in Example 1.

Volume average particle size 11.04 as in Example 1 except that 5 parts of Pigment Blue 15) was replaced with 3 parts of carbon black.
A fine powder of m was obtained, and silica was further mixed therein to obtain a positively charged toner.

Next, 7 batches of the same carrier as in Example 1 were combined at the same ratio to prepare a developer.

This developer was subjected to a copying test in the same manner as in Example 1. As a result, under the environmental conditions of 23° C. and 60%, a bright black image with a density of 1.38 was obtained from the beginning. 20
No deterioration in image quality was observed even after making ,000 copies.

Example 5 I [A full-color image was obtained using the cyan, magenta, yellow, and black developers used in Examples 1 to 4, and a bright full-color image with excellent color mixing and gradation was obtained.

A toner was obtained in the same manner as in Example 1, except that 3 parts of benzylmethylhexadecyl ammonium chloride was used instead of 3 parts of the zinc complex used in Example 1. Using this toner, an image was obtained in the same manner as in Example 1.

From the beginning, the image density was slightly low at 1.15, and fog was noticeable. Although s and ooo sheets were continuously copied, no increase in image density was observed.

After thoroughly mixing the above materials in a blender, they were kneaded in a twin-screw kneading extruder set at 150°C.

The obtained kneaded material was cooled, coarsely pulverized using a cutter roll, and then finely pulverized using a pulverizer using a jet stream.
The obtained finely pulverized powder was classified using a fixed wall type wind classifier.

Furthermore, the obtained classified powder was strictly classified and removed at the same time using a multi-division classifier (elbow jet classifier manufactured by 0 Tetsu Mining Co., Ltd.) using the Coanda effect to achieve a volume average particle size of 10.5.
A fine powder of μm size was obtained.

To 100 parts of the obtained fine powder, 0.4 part of positively charged hydrophobic dry silica (BET specific surface area 200 m" 7g) treated with silicone oil having an amino group was added and mixed in a Henschel mixer to form a positively charged toner. And so.

Next, 9 parts of the obtained toner were mixed with 100 parts of an acrylic coated ferrite carrier having an average particle size of 65 μm to prepare a developer.

This developer was applied to a commercially available color electrophotographic copying machine CLC-1 (
A copying test was conducted using a modified machine in which the OPC 6-optical drum (manufactured by Canon ■) was replaced with an amorphous silicon drum.

As a result, under the environmental conditions of 23°C and 60%, a bright blue image with a density of 1.37 was obtained from the initial stage, and 20,000
No deterioration was observed after copying.

A developer was prepared in the same manner as in Example 6 without externally adding positively charged hydrophobic dry silica to the fine powder obtained in Example 6, and a copying test was conducted.

The image density was as low as 1.03, and the image was rough, cracked, and fogged.

After thoroughly mixing the above materials in a blender, they were kneaded in a twin-screw kneading extruder set at 150°C.

The obtained kneaded material was cooled and coarsely pulverized using a cutter mill, and then finely pulverized using a pulverizer using a jet stream.
The obtained finely pulverized powder was classified using a fixed wall type wind classifier.

Furthermore, the obtained classified powder was strictly classified and removed at the same time using a multi-division classifier (elbow jet classifier manufactured by 0 Tetsu Mining Co., Ltd.) using the Coanda effect to obtain a volume average particle size of 11.2.
A fine powder of μm size was obtained.

To 100 parts of the obtained fine powder was added 0.6 parts of positively charged hydrophobic dry silica (BET specific surface area 200 m"7 g) treated with dimethylaminopropyltrimethoxysilane,
The mixture was mixed using a Henschel mixer to obtain a positively chargeable toner.

Next, 7 parts of the obtained toner were mixed with 100 parts of an acrylic coated ferrite carrier having an average particle size of 65 μm to prepare a developer.

This developer was applied to a commercially available color electrophotographic copying machine CLC-1 (
A copying test was conducted using a modified Canon machine that replaced the OPC photosensitive drum with an amorphous silicon drum.

As a result, under the environmental conditions of 23°C and 60%, a bright blue image with a density of 1.35 was obtained from the initial stage, and 20,000
No deterioration was observed after copying.

A black fine powder (volume average particle diameter: 8.9 μm) was obtained from the above material by the method of Example 1.

To 100 parts of the obtained fine powder, 0.9 parts of positively charged hydrophobic dry silica (CBET specific surface area 200 m"7g) treated with silicone oil having an amino group was added and mixed in a Henschel mixer to form a positively charged toner. did.

Next, 9 parts of the obtained toner were mixed with 100 parts of silicon-coated ferrite carrier having an average particle diameter of 100 μm to prepare a developer.

This developer was applied to a commercially available color electrophotographic copying machine CLC-1 (
A copying test was conducted using a modified Canon machine in which the OPC photoreceptor drum was replaced with an amorphous silicon drum.

As a result, a bright black image with a density of 1.35 was obtained from the initial stage under the environmental conditions of 23°C and 60%, and 10,000
Good images were obtained even after printing.

100 parts of styrene/n-butyl methacrylate The above materials were thoroughly mixed in a blender, and then kneaded in a twin-screw kneading extruder set at 150°C.

The obtained kneaded material was cooled and coarsely pulverized using a cutter mill, and then finely pulverized using a pulverizer using a jet stream.
The obtained finely pulverized powder was classified using a fixed wall type wind classifier.

Furthermore, the obtained classified powder was strictly classified and removed at the same time using a multi-division classifier (elbow jet classifier manufactured by 8 Iron Mining Co., Ltd.) that utilizes the Coanda effect to achieve a volume average particle size of 11.5.
A fine powder of μm size was obtained.

To 100 parts of the obtained fine powder, 0.5 part of positively charged hydrophobic dry silica (BET specific surface area t: +am'/g) treated with silicone oil having an amino group was added, and mixed with a Henschel mixer. It was made into a chargeable toner.

Next, 5 parts of the obtained toner were mixed with 100 parts of a fluorine-acrylic coated ferrite carrier having an average particle size of 65 μm to prepare a developer.

When this developer was applied to a commercially available copying machine (trade name NP-5540, manufactured by Canon ■) and an image was produced, an image of good quality with an image density of 1.28 was obtained.

Using the above developer, 5,000 sheets were continuously copied to examine the durability. As a result, good images comparable to the initial images were obtained.

[Effects of the Invention] As described above, the positively chargeable component-based magnetic toner of the present invention has a uniform amount of triboelectric charge between toner particles, and provides a high-density, clear image without fogging, scattering, or roughness. .

Furthermore, since there is less contamination of toner carriers and other toner carriers, it has excellent durability, and even if the number of copies is repeated, there is only one friction band! The amount is stable and the image density is also stable.

Claims (4)

[Claims] (1) A toner for developing an electrostatic image, characterized in that a positively chargeable silica fine powder is externally added to fine powder particles comprising at least a metal compound of an imidazole derivative, a dye/pigment, and a binder resin. (2) As the metal compound of the imidazole derivative, zinc,
2. The toner for developing electrostatic images according to claim 1, which contains an imidazole metal compound having titanium, nickel, iron, copper, chromium, or cobalt as a central metal. (3) Positively chargeable silica fine powder has the formula R_
mSiY_n [wherein R represents an alkoxy group or halogen, m represents an integer of 1 to 3, Y represents an amino group or an organo group having at least one nitrogen atom,
n represents an integer of 1 to 3 such that m+n is 4. The toner for developing an electrostatic image according to claim 1, which is treated with a silane compound represented by the following. (4) The toner for developing electrostatic images according to claim 1, wherein the positively chargeable silica fine powder is obtained by treating the silica fine powder with a silicone oil having an organo group or an amino group having a nitrogen atom in a side chain.